JP3116844B2 - Color plasma display panel and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color plasma display panel used for an information display terminal, a flat panel television, and the like, and particularly to a panel structure for high contrast, high luminance, and high luminous efficiency.

[0002]

2. Description of the Related Art A color plasma display panel is
This is a display that performs a display operation by exciting and emitting a phosphor by ultraviolet light generated by gas discharge. The discharge type can be classified into an AC type and a DC type. Among them, the AC type is superior to the DC type in terms of luminance, luminous efficiency, and life, and among the AC types, the reflective AC surface discharge type has the luminance,
It is excellent in terms of luminous efficiency.

FIG. 14 shows a cross section of an example of a conventional reflection type AC surface discharge color plasma display panel. A transparent electrode 2 is formed on a front substrate 1 which is a transparent glass plate on the display surface side. A plurality of the transparent electrodes are formed in a band shape in a direction parallel to the paper surface. This adjacent transparent electrode 2
During this period, a pulsed AC voltage of several tens kHz to several hundreds kHz is applied to obtain a display discharge.

For the transparent electrode 2, tin oxide (SnO ₂ ) or indium tin oxide (ITO) is used.
In order to reduce the resistance, a metal thin film such as a multilayer thin film of chromium / copper / chromium or an aluminum thin film, or an electrode provided with a bus electrode formed of a thick metal film such as silver is used.
When a thick silver film is formed, a slight amount of black pigment is often mixed. However, the bus electrode is omitted in FIG.

The transparent electrode 2 is covered with a transparent insulating layer 17. This transparent insulating layer 17 has a current limiting function peculiar to the AC plasma display. The transparent insulating layer 17 is usually formed by applying a paste mainly composed of a low-melting-point lead glass, baking it at a high temperature equal to or higher than the softening temperature, and reflowing it for the purpose of withstand voltage and ease of manufacture.
As a result, a smooth transparent insulating layer 17 having a thickness of about 20 μm to 40 μm and containing no bubbles or the like is obtained. On this, a black matrix layer 30 of black color is formed. This has the effect of reducing external light reflection on the display surface and also has the effect of preventing erroneous discharge and optical crosstalk between adjacent discharge cells. This black matrix 3
0 is usually formed by forming a paste made of a metal oxide powder such as iron, chromium, nickel or the like and a low melting point lead glass by thick film printing or the like.

Next, a protective layer 16 is formed so as to cover the whole of the transparent insulating layer 17 and the black matrix layer 30. The protective layer 16 is a thin film of MgO formed by vapor deposition or sputtering, or a thick film of MgO formed by printing, spraying, or the like. The film thickness is about 0.5 to 2 microns. The role of this protective layer is to reduce discharge voltage and prevent surface spatter.

On the other hand, on a rear substrate 8 which is a glass plate,
A data electrode 9 for writing display data is formed.
In FIG. 14, the data electrodes 9 extend in the direction perpendicular to the paper surface, and are formed for each of the discharge cells 18 to 20. That is, the data electrode 9 is orthogonal to the transparent electrode 2 formed on the front substrate 1 which is a glass plate. This data electrode 9 is
A thick film paste in which a low melting point lead glass and a white pigment are mixed is covered with a white insulating layer 7 formed by printing and baking. As the white pigment, titanium oxide powder or alumina powder is usually used. A white partition 6 is formed on the white insulating layer 7 by a normal thick film printing or a sand blast method, and a discharge cell 18, a discharge cell 19 and a discharge cell 20 are provided with a phosphor (red) corresponding to the emission color of each cell. ) 10, phosphor (green) 11 and phosphor (blue) 12 are applied. Each phosphor is also formed on the side surface of the white partition wall 6 in order to increase the phosphor application area and obtain high luminance. Normally, screen printing is used for forming each phosphor.

The above-mentioned pattern of the black matrix layer 30 formed on the front substrate 1 and the white partition 6 formed on the rear substrate 8 are bonded and hermetically sealed so as to be overlapped with each other, so that the discharge inside the discharge cells 18 to 20 can be performed. A gas such as a mixed gas of He, Ne and Xe is sealed at a pressure of about 500 torr.

In FIG. 14, two transparent electrodes 2 are arranged in each of the discharge cells 18 to 20, and a surface discharge occurs between the transparent electrodes, and a discharge cell (red) 18 and a discharge cell (green) 1
9 and the discharge cell (blue) 20 generate plasma. The phosphor (red) 10 and the phosphor (green) are generated by ultraviolet light generated at this time.
Excitation of the phosphor 11 (blue) 12 generates visible light, and display light emission is obtained through the front substrate 1.

[0010] A pair of adjacent transparent electrodes 2 for generating a surface discharge serve as a scanning electrode and a sustaining electrode, respectively. In actual panel driving, a sustain pulse is applied between the scan electrode and the sustain electrode. When a write discharge is generated, a voltage is applied between the scan electrode and the data electrode 9 to generate a counter discharge, and a sustain pulse is applied between the scan electrode and the data electrode 9 to generate a sustain discharge between the surface discharge electrodes.

FIG. 5 shows another conventional example. This is a configuration in which the thickness of the black matrix 30 in FIG. The basic process is the same as in FIG. The black partition 5 is usually formed by screen printing or sandblasting. The material is a low melting point lead glass, a filler material such as alumina, and a black pigment. The same black pigment as the black matrix 30 is used. In this structure, the phosphor application area is smaller than in the structure of FIG. 14, so that the brightness is slightly lowered. However, since the phosphor at the top of the white partition wall 6 has a certain distance from the surface discharge generated along the front substrate 1. Another advantage is that there is little change in luminance due to long-time lighting.

The phosphor used in the color plasma display panel is a white powder having a very high reflectance. In the conventional color plasma display panel of FIG. 14 or FIG. 5 described above, when indoor (outdoor) light (outside light) enters the panel, the outside light is absorbed by the black matrix or black partition or the bus electrode portion. % To 50%
The degree is reflected and the contrast and color purity are significantly impaired. For this reason, a panel surface having a transmittance of about 40 to 80% of N
Although there is a method of arranging a D filter, there is a drawback that panel luminance is reduced because light emission of the panel is also blocked.

As a method for suppressing the reflection of external light without reducing the panel luminance as much as possible, there is a method using a micro color filter. This is to form a color filter that transmits red, green, and blue light on the display surface side corresponding to the emission colors from the red, green, and blue discharge cells. As a micro color filter of a plasma display, a method of directly forming a micro color filter on a glass substrate surface and a method of forming an insulating layer of an AC type plasma display with a colored glass layer are known. FIG. 15 shows a cross section of a conventional example of a color plasma display panel using the latter method. In this example, a color filter that allows the emission colors of the discharge cells (red) 18, the discharge cells (green) 19, and the discharge cells (blue) 20 to be formed on the transparent electrode 2. 14 differs from FIG. 14 in that the transparent insulating layer 17 covering the discharge electrode is provided with a color filter (red) 13, a color filter (green) 14, and a color filter (blue) composed of a colored low melting point lead glass layer.
15 is replaced. This structure is described in, for example,
No. 36930. As a result, the attenuation of the light emitted from each of the discharge cells 18 to 20 is minimized, the reflection of external light is suppressed, and the contrast is improved.

The color filters 13 to 15 are usually prepared by mixing a low melting point lead glass powder and a pigment powder, printing a filter paste containing an organic solvent and a binder for each color by screen printing, and baking. , Formed as an insulating layer of colored low melting point lead glass. In addition, since the pigment powder needs to withstand a firing process at a high temperature (500 ° C. to 600 ° C.), an inorganic material is selected.
Representative pigment powders are shown below.

Red: Fe ₂ O ₃ system Green: CoO—Al ₂ O ₃ —TiO ₂ —Cr ₂ O ₃ system Blue: CoO—Al ₂ O ₃ system The above filter paste corresponds to three colors of red, green and blue. Then, printing is performed three times to form the entire color filter layer.

FIG. 6 shows a case where a black partition 5 is formed in place of the black matrix 30 with the same structure.

This color filter layer needs to have a thickness of 20 μm or more in order to function as an insulating layer having a sufficient withstand voltage, so that dents and bulges are formed at seams for each color of the color filter. This also has an adverse effect on dielectric breakdown and a process of a black matrix and a black partition wall in a later process.

In order to avoid the above-mentioned adverse effects, Japanese Patent Laid-Open Publication No. Hei 7-21924 discloses that a transparent insulating layer 4 further covers the colored filters 13 to 15 of low melting point lead glass colored as shown in FIG. There is known a method for smoothing the entire surface of a color filter. Further, in order to realize the structure shown in FIGS. 15 and 6, in Japanese Patent Application Laid-Open No. H4-249032,
A method is disclosed in which a low-melting-point lead glass paste is printed on the entire surface after the coloring pigments of each color are separately applied and baked to diffuse and disperse the pigment in the glass layer.

[0019]

A conventional color filter layer formed by dispersing a pigment powder in a low-melting-point lead glass has a problem that light is scattered because the pigment and the low-melting-point lead glass have different refractive indices. Occurs. For this reason, there is a disadvantage that the parallel light transmittance of the filter is deteriorated. The term “parallel light transmittance” as used herein refers to a transmittance of light that passes through a filter almost linearly, and does not include a component of light scattered by the filter. Since the color filter layer has a large scattering property, the external light is backscattered. For this reason, the effect as a color filter is impaired. In other words, the screen becomes cloudy and the color of the color filter itself looks more intense. Further, there is a problem that the emission color from the discharge cell is reduced due to scattering by the color filter, and the luminance is reduced. Further, depending on the materials used and the process conditions, the pigment is often not uniformly dispersed in the low-melting-point lead glass film and aggregates, and the performance as a color filter may be extremely deteriorated. Further, when the color pigment is dispersed in the low melting point lead glass, there is a problem that the color is changed or the color is changed due to the reaction with the glass.

Further, as a result of a detailed experiment, the transparent electrode made of ITO or Nesa film reacts with the pigment at the time of firing at a high temperature, and the color filter performance may be impaired. For example, CoO-Al which is excellent as a blue pigment
_{In the case of 2} O ₃ pigments, the baking process causes light absorption at a wavelength of about 400 nm, which significantly reduces the transmittance as a blue filter, which leads to a reduction in panel luminance and a loss of color balance. there were. Further, the red filter paste using the Fe ₂ O ₃ pigment also has a problem that a large amount of discoloration occurs due to the reaction with the transparent electrode, and the function of the color filter is reduced. It is unknown whether these phenomena are a direct reaction or a catalytic action of the transparent conductive film material, but it is a problem to be solved to realize a good color filter.

As described above, in addition to the performance degradation as a color filter, in a configuration in which a coloring pigment is dispersed in a low-melting-point lead glass, reflow by firing is involved.
There also arise problems that the fine color filter pattern shifts or spreads from a predetermined pixel to the periphery.

Due to these problems, a color plasma display panel with a good display performance and a good color filter has not been put to practical use.

As described above, an object of the present invention is to increase the parallel light transmittance of a color filter to reduce discomfort such as white turbidity on a screen, or to use a pigment powder and a transparent electrode material, or a pigment powder and a low melting point lead. An object of the present invention is to prevent a change in transmission spectrum due to reaction with glass and realize a color filter having good characteristics.

[0024]

An AC type color plasma display panel according to the present invention has a transparent electrode coated on an insulating layer, and the insulating layer directly covers the transparent electrode with a buffer layer and a color filter. It has at least a two-layer structure in which an insulating layer having a function is stacked.

In the AC type color plasma display panel according to the present invention, the buffer layer may be a low melting point lead glass,
Alternatively, it is made of alumina or silicon oxide.

In the AC type color plasma display panel according to the present invention, the transparent electrode is preferably made of tin oxide or IT.
Consists of O.

In the AC type color plasma display panel according to the present invention, the insulating layer having the function of the color filter is formed by printing a mixture of a low melting point lead glass and a pigment powder.

In the AC type color plasma display panel according to the present invention, the insulating layer having the function of the color filter is formed by printing and firing a pigment powder first, and coating and firing a transparent low melting point lead glass thereon. .

In the AC type color plasma display panel according to the present invention, the insulating layer having the function of the color filter is formed by patterning a mixture of a pigment powder and a photosensitive material by photolithography, and then forming a transparent low melting point. It is formed by coating and firing with lead glass.

An AC type color plasma display panel according to the present invention has at least a discharge electrode and an insulating layer on a front substrate which is a display surface side, and has pigment fine particles in contact with the insulating layer or inside the insulating layer. Is formed as a thin color filter layer.

In the AC type color plasma display panel according to the present invention, a thin color filter layer containing the pigment fine particles as a main component is formed on the insulating layer.

In the AC color plasma display panel according to the present invention, after a thin color filter layer mainly composed of the pigment fine particles is formed on a substrate including a discharge electrode, the insulating layer covers the color filter layer. It is formed.

In the AC type color plasma display panel according to the present invention, after the insulating layer is formed on the substrate including the discharge electrode, a thin color filter layer containing the pigment fine particles as a main component is formed. An insulating layer is formed to cover the filter layer.

In the AC type color plasma display panel according to the present invention, the insulating layer comprises at least two or more insulating layer components, and is provided on at least one surface of the thin color filter layer containing the pigment fine particles as a main component. The softening point of the contacting insulating layer component is higher than the softening point of at least one of the other insulating layer components.

In the AC color plasma display panel according to the present invention, the thin color filter layer containing the pigment fine particles as a main component has a thickness of 0.5 to 5 μm.

In the AC type color plasma display panel according to the present invention, the thin color filter layer mainly composed of the pigment fine particles has a thickness of 0.5 to 3 μm.

In the AC type color plasma display panel according to the present invention, the thin color filter layer containing the pigment fine particles as a main component is formed of pigment powder having an average particle size of 0.01 to 0.15 μm.

[0038] In the method of manufacturing a color plasma display panel according to the present invention, the insulating layer is formed of at least two layers, and the insulating layer directly covering the color filter layer from above does not adversely affect the color filter layer. And a second firing step in which the firing temperature of at least one of the other insulating layers is higher than that of the first firing step.

[0039]

(First Embodiment) A cross-sectional structure of a color plasma display panel according to a first embodiment of the present invention will be described with reference to FIG. The rear substrate is exactly the same as that of the conventional example shown in FIG. 14, and the rear substrate 8 has a data electrode 9, a white partition 6, a phosphor (red) 10, a phosphor (green) 11, a phosphor (blue) 12 Are sequentially created, and the discharge cells 1 of each emission color are formed.
8, 19, and 20 spaces were formed. The white partition 6 has a pitch of, for example, 350 microns, and the width of the white partition 6 is about 8
0 microns. A transparent electrode 2 was formed on a front substrate 1, and a metal bus electrode for lowering the resistance was formed thereon (not shown). Next, the paste of the low melting point lead glass is screen-printed and baked at about 580 ° C. to form a transparent insulating layer 17 made of a molten glass layer having a thickness of about 25 μm.
Was formed. On this substrate, a color filter layer of each color was formed by the following steps. A paste prepared by mixing a binder and a solvent with a red fine particle pigment containing iron oxide as a main component was screen-printed in a stripe shape having a pitch of 1.05 mm and a width of about 390 μm, and the solvent was evaporated at about 150 ° C. and dried. Subsequently, cobalt, chromium, aluminum,
Using a paste prepared by mixing a binder and a solvent with a green fine particle pigment mainly composed of titanium oxide, screen printing was performed adjacent to a position shifted 350 microns in parallel from the already printed red pigment pattern, and dried. Finally, a paste composed of a blue pigment mainly containing cobalt and aluminum oxide fine particles, a binder, and a solvent was printed and dried by the same method. By printing the coloring pigment three times, a portion corresponding to the display portion was entirely covered with pigments of each color, and then baked at about 520 ° C. By this step, a pigment fine particle layer (red) 25, a pigment fine particle layer (green) 26, and a pigment fine particle layer (blue) 27 are formed.

The firing temperature at the time of forming the transparent insulating layer 17 of the low-melting-point lead glass is a high temperature in order to melt the low-melting-point lead glass and to form a smooth and transparent insulating layer having no bubbles inside. On the other hand, for baking the pigment fine particle layer on the insulating layer, a temperature at which the low melting point lead glass layer does not reflow much is selected. If the firing temperature is increased, the underlying low-melting-point lead glass insulating layer flows, causing the pattern of the pigment layer printed in a good shape to be deformed or cracking. When the layer and the pigment fine particle layer are mutually diffused, the scattering property becomes strong, and the reaction with the low melting point lead glass causes a change in the transmission spectrum, thereby causing a problem that the good performance as a color filter is impaired. . Therefore, in order to realize a thin color filter layer containing the pigment fine particles of the present invention as a main component, the temperature is higher than the temperature at which the binder component contained in the pigment paste is sufficiently decomposed and burned, and lower than the temperature at which the insulating layer hardly reflows. And it was. In this embodiment, at 520 ° C., which is about 10 ° C. higher than the softening point of the low melting point lead glass used for the insulating layer.
Sintering temperature. At this temperature, no flow or diffusion that deforms the pattern of the pigment fine particle layer occurs, but the surface of the insulating layer is slightly softened, so that the effect of strongly fixing the pigment fine particle layer was obtained. The thickness of the color filter layer after firing is about 1
Micron to 2 microns. Of course, the pigment fine particles themselves are not melted at this temperature, so that the pattern does not collapse due to reflow unlike a conventional color filter.

Next, a front substrate was completed by vacuum-depositing a protective layer 16 of an MgO film directly on the color filter layer. The particle size of the used inorganic pigment fine particles is 0.
It was a very fine and dense layer of about 01 to 0.15 microns, and did not peel off even when the MgO film was directly deposited. Finally, combined with the rear substrate, sealing, exhausting, and sealing of discharge gas were performed to complete a plasma display panel with a color filter.

In the case of a large-area plasma display panel, the screen printing accuracy may be insufficient. At this time, if a gap is formed between the adjacent pigment fine particle layer patterns, the display surface becomes significantly uneven and the quality is impaired. It formed so that it might overlap. Since the overlapping portion is located on the partition wall portion that does not emit light, not only does not cause any inconvenience due to the overlapping, but also a strongly colored black matrix contributes to the improvement of contrast under external light. Of course, the pigment fine particle layers of each color may be formed without overlapping for convenience of manufacture.

In the plasma display panel of the present embodiment, since the color filter layer is not dispersed in the low melting point lead glass insulating layer, there is no reaction deterioration or scattering with the low melting point lead glass, and very little. Because of the thin layer composed mainly of fine pigment particles having a fine particle diameter, good color filter characteristics with high parallel transmittance were obtained.

(Second Embodiment) In the above structure, the color filter layer made of pigment fine particles does not have high mechanical strength, so that the color filter layer peels off due to contact during assembly with the rear substrate. There was a problem. Also,
It was difficult to form a black matrix layer and the like after forming the color filter. Therefore, as a second embodiment, an example in which a color filter layer is formed before forming a transparent insulating layer is described with reference to FIG. After a transparent electrode 2 and a metal bus electrode (not shown) were formed on the front substrate 1, color filter layers of each color were formed in the same manner as in the first embodiment. A paste prepared by mixing a binder and a solvent with a red fine particle pigment containing iron oxide as a main component, at a pitch of 1.05 mm,
It was screen-printed into a stripe of about 340 microns wide and dried. Subsequently, using a paste prepared by mixing a binder and a solvent with a green fine particle pigment mainly containing oxides of cobalt, chromium, aluminum, and titanium, and adjacent to a position shifted 350 μm from the already printed red pigment pattern. Screen printed and dried.
Lastly, a paste composed of a blue pigment mainly composed of cobalt and aluminum oxide fine particles, a binder, and a solvent was printed, dried, and fired in the same manner, and the binder was blown off and fixed. By printing the color pigments three times, the entire surface corresponding to the display portion has a red, green,
It is covered with blue pigment fine particle layers 25, 26, 27. A low-melting lead glass paste is screen-printed on this substrate,
After drying, firing was performed to form a first insulating layer 28. Further, another low melting point lead glass paste was applied thereonto, dried and fired again to form a second insulating layer 29.

The formation of the first and second insulating layers made of a low melting point lead glass on the pigment fine particle layer requires special attention. That is, when the firing temperature of the low melting point lead glass layer is high,
At the time of firing, the pigment fine particles are diffused into the glass layer, and the pattern of the pigment layer is disturbed by the flow. In addition, cracks occurred in the color filter layer even when it did not flow significantly. In the case of a very narrow crack, the effect is substantially small, but a crack as large as 50 microns may occur. Since the cracks are transparent, they significantly reduce the filter function. Dependence of the occurrence of cracks on the pigment material and particle size was observed. In particular, a green pigment and a very fine particle pigment of 0.01 μm or less were more remarkable.

In the present embodiment, in order to cope with this problem, the insulating layer of low melting point lead glass has a two-layer structure. That is, the first insulating layer 2 directly covering the pigment fine particle layers 25 to 27
For No. 8, a low melting point lead glass powder having a higher softening point than the second insulating layer 29 was used. In the embodiment, a paste made of glass powder having a softening point of 520 ° C. as a raw material is applied on the pigment fine particle layer, dried, and fired at 535 ° C. to form a thin first insulating layer 28 of about 7 μm. It was formed so as to cover the pigment fine particle layer. In this step, since the difference between the sintering temperature and the softening point temperature of the first insulating layer is small, the flowability of the low-melting lead glass during sintering is low and the pigment fine particle layer has cracks, aggregation,
Does not adversely affect the glass layer, such as dispersion and diffusion. However, since the firing temperature is low, the smoothness of the surface of the first insulating layer 28 is not so good, and there is fine waviness. Also, defects such as fine pinholes remain,
The dielectric strength as an insulating layer was not very good. Therefore, after forming the first insulating layer 28, a paste made of a low melting point lead glass having a low softening point was printed, dried, and fired to form the second insulating layer 29. The firing temperature is selected to be a temperature at which a reflowed and smooth surface and a high pressure-resistant insulating layer free of pinholes and bubbles are formed. In the embodiment, a low-melting-point lead glass material having a softening point of 490 ° C. is used, and firing is performed at 570 ° C. Since the pigment fine particle layer serving as the color filter layer is already covered with the first insulating layer 28 having a high softening point temperature, even when the second insulating layer 29 is fired, diffusion of the pigment does not occur, and a thin pigment layer is formed. The shape of the layer was maintained.
In addition, neither deformation nor cracking of the pigment pattern due to the flow occurred.

Finally, a protective layer 16 of an MgO film was deposited to complete a front substrate. A plasma display panel was completed by combining with a rear substrate and filling a discharge gas.

(Third Embodiment) As an embodiment of the third invention, a buffer layer 3 which is a transparent insulating layer is first formed on an electrode in FIG. 10, and then a pigment fine particle layer is formed.
An example in which a transparent insulating layer is further formed will be described. After a transparent electrode 2 is formed on a front substrate 1 which is a glass plate, and a metal bus electrode (omitted in FIG. 10) is further formed thereon, a low-melting-point lead glass paste is applied to the entire surface, dried and fired. Thereby, the transparent electrode or the metal electrode is covered with the buffer layer 3 which is a transparent insulating layer. The buffer layer 3 serves as a base for forming the subsequent pigment fine powder layer. After the formation of the buffer layer, a pigment fine particle layer of each color was formed in the same manner as in the second embodiment. That is, a paste in which a binder and a solvent are mixed with pigment fine particles is screen-printed in a stripe shape having a pitch of 1.05 mm and a width of about 340 microns, and a process of drying is repeated in three colors. 27 was formed. From above, screen printing application of low melting point lead glass paste, drying,
The firing is performed twice, and the first insulating layer 28 and the second insulating layer 29 are formed.
Was formed. Here, the buffer layer 3 serving as an underlayer formed prior to the pigment fine particle layer has a softening point of 520 ° C.
Was fired at 570 ° C. and sufficiently reflowed.
First insulating layer 2 formed to directly cover pigment fine particle layer
8, the same softening point of 520 ° C. was used. Further, the second insulating layer 29 formed thereon has a temperature of 490 ° C.
And low-melting lead glass with a low softening point and a firing temperature of 5
The temperature was increased to 70 ° C. In this manner, similarly to the second embodiment, an insulating layer having a sufficiently high withstand voltage and excellent surface smoothness was obtained, and deterioration of the color filter characteristics due to the formation of the insulating layer was avoided.

The main difference between this embodiment and the second embodiment is that an insulating layer serving as a base is formed before forming a pigment fine particle layer. First of all, as an effect of this treatment, uniformity was improved. In the case of the second embodiment, the pigment fine particle layer has three different types of components (glass plate, I
In order to cover the surface of a transparent conductive film such as TO or tin oxide, or the metal film of the bus electrode), when the printing thickness becomes uneven or the reaction or agglomeration occurs due to the combination of the base material and the pigment material in the firing process, resulting in unevenness. was there. In particular, this tendency was strong for red pigments and blue pigments. As described in the present embodiment, the above-described problem does not occur and a good color filter layer is obtained by covering the front surface of the glass plate portion, the transparent electrode portion, and the metal electrode portion with the buffer layer 3 serving as a base. I was able to. The buffer effect as the underlayer exerted a sufficient underlayer effect even with a thickness of about 3 microns. Of course, a thick layer of 20 microns or more may be used in order to sufficiently increase the withstand voltage. In this case, the second insulating layer 29 of the present embodiment can be omitted, and a substantial withstand voltage characteristic can be given to the buffer layer serving as a base.

FIG. 10 shows an example in which a thin black matrix 30 is formed between the color filter layers of each color before the protective layer 16 of the MgO film is deposited. The black matrix 30 can cover the non-light-emitting white partition 6 and also hide the pattern shift of the color pigment layer, thereby contributing to the contrast and the uniformity of the display surface.

Here, the reaction caused by the combination of the pigment material in the baking step and the base material for forming the pigment layer will be described in detail. The underlying material that poses a problem here is tin oxide or ITO (indium tin oxide), which is a material for the transparent electrode. Although this reaction may occur even when a pigment fine powder layer is formed, it is particularly likely to occur when a paste in which a pigment powder and a low melting point lead glass are mixed is printed on a transparent electrode and dried and fired. Hereinafter, the case where the pigment powder is mixed with a low melting point lead glass and printed, dried and fired will be described in detail as an example.

FIG. 1 shows another example of the third embodiment of the present invention. FIG. 7 shows a conventional example corresponding to FIG.
The same members will be described with the same reference numerals.

The structure of the insulating layer covering the transparent electrode 2 is different between the AC color plasma display panel of FIG. 1 and the conventional AC color plasma display panel shown in FIG. That is, in the AC type color plasma display panel of FIG. 1, a buffer layer 3 is formed on a transparent electrode 2 and a color filter (red) 1 is formed thereon.
3, the color filter (green) 14 and the color filter (blue) 15 are connected to the discharge cell (red) 18 and the discharge cell (green) 1
9. Formed corresponding to the emission color of the discharge cell (blue) 20, and cover the transparent insulating layer 4 thereon.

At this time, the color filter (red) 13, the color filter (green) 14, and the color filter (blue) 1
5 is usually a mixture of a low melting point lead glass powder and a pigment powder,
Then, a filter paste obtained by mixing an organic solvent and a binder is formed by printing, drying and baking for each color by screen printing. The material of the pigment powder may be the same as that described in the above embodiment. Accordingly, the pigment powder is in a form dispersed in an insulating layer of low melting point lead glass, and is completely different from the pigment fine particle layer (red) 25, the pigment fine particle layer (green) 26, and the pigment fine particle layer (blue) 27. Also distinguished and described on the symbols.

In this structure, since the buffer layer 3 is provided,
There is no direct contact between the transparent electrode 2 and the color filters 13, 14, and 15. Therefore, it is possible to prevent a reaction between tin oxide (SnO ₂ ) or ITO, which is a raw material of the transparent electrode 2, and an inorganic pigment, which is a main component of the color filter.

On the other hand, if a color filter is formed directly on the transparent electrode 2 without using the buffer layer 3,
A reaction occurs between tin oxide (SnO ₂ ) or ITO in the transparent electrode 2 and the inorganic pigment which is a main component of the color filter. The detailed mechanism of this reaction has not yet been elucidated. How the transmission spectrum of the color filter changes due to this reaction will be described below.

In the graph of FIG. 3, reference numeral 21 indicates a transmission spectrum curve when a color filter (blue) 15 using a blue pigment is baked on tin oxide (SnO ₂ ) according to the conventional example, and 22 indicates the present invention. 7 shows a transmission spectrum curve when a color filter using a blue pigment is baked on a buffer layer 3 of low melting point lead glass according to the embodiment of FIG. The firing temperature of the color filter paste is 550 ° C.

When comparing the curves 21 and 22, the curve 21
It can be seen that light having a wavelength near 400 nm is more strongly absorbed.

Since the wavelength of the light emitted from the blue phosphor is around 455 nm, it is affected by the above-mentioned absorption, and when the blue filter is baked on SnO ₂ , the transmittance is greatly reduced. FIG. 3 shows the change in the transmittance in that case, and almost the same change in the transmission spectrum can be seen when firing on ITO.

In FIG. 4, a curve 23 shows a transmission spectrum when a color filter (red) 13 using a red pigment is baked on tin oxide (SnO ₂ ) according to a conventional example, and a curve 24 shows an embodiment of the present invention. The transmission spectrum when the red filter paste is baked on the buffer layer 3 of low melting point lead glass according to the form is shown. Again, the color filter paste was fired at 550 ° C.

The light emitted by the red phosphor has a wavelength near 610 nm. As can be seen from the curve 24, when a color filter using a red pigment is baked on the buffer layer, the transmittance on the short wavelength side decreases from around 610 nm and the color filter functions as a color filter.
₂ ) When a color filter using a red pigment was fired thereon, the color was remarkably faded as shown by curve 23,
The transmittance hardly changes up to around nm, and the filter cannot function as a filter. FIG. 4 shows a change in transmittance in the case of a transparent electrode of tin oxide (SnO ₂ ), and almost the same change in transmittance is observed on ITO.

As for the green color filter,
No change in the transmission spectrum was observed even after firing on the transparent electrode.

That is, the color plasma display panel of FIG. 1 has the transparent electrode 2 and the color filters 13, 14,
By forming the buffer layer 3 on the transparent electrode 2 so that the transparent electrode 15 does not come into direct contact with the transparent electrode 2, tin oxide (SnO ₂ ) or ITO as a raw material of the transparent electrode 2 and an inorganic pigment which is a main component of a color filter are formed. The reaction is prevented and the change in transmittance is prevented.

This embodiment is based on a completely new finding that the transmission spectrum of a color filter formed directly on a transparent electrode changes.

FIG. 2 is a cross section of another example of the AC type color plasma display panel according to the present embodiment.

This color plasma display panel has a basic structure similar to that of the conventional AC type color plasma display panel shown in FIG. 7, but has a transparent insulating layer for smoothing the surfaces of the color filter layers 13, 14, and 15. The color filter layer 13 in which the layer 4 is removed and the pigment powder is dispersed in the transparent electrode 2 and the low melting point lead glass,
14 and 15 in that the buffer layer 3 is inserted. Also in this case, since the transparent electrode 2 does not directly contact the color filter layers 13 to 15, the transmittance does not change.

The color filter layer in the embodiment described here is obtained by printing a mixture of a pigment and a low melting point lead glass. As described above, a similar effect can be obtained by printing only the pigment powder first, coating this with a transparent low-melting-point lead glass, and firing. A similar effect can be obtained by mixing a photosensitive material with the pigment powder, forming a color filter layer by photolithography, coating with a transparent low-melting-point lead glass, and firing.

The most suitable material for the buffer layer 3 in FIGS. 1, 2 and 10 is a low melting point lead glass. However, besides this, as the buffer layer 3, for example, alumina may be formed to a thickness of about 1 to 3 μm by vacuum evaporation. This also has a sufficient effect of the buffer layer.

If another material is used, SiO2 or the like can be used. It is also possible to form a buffer layer by sputtering or dipping SiO2. Similar effects are often obtained with materials other than the above.

That is, an effect almost equivalent to that of the buffer layer made of low melting point lead glass can be expected. However, considering the compatibility with the process, the cost, and the like, it can be said that the buffer layer of low melting point lead glass is optimal.

(Fourth Embodiment) In the second embodiment, the insulating layer made of low melting point lead glass has a two-layer structure having different softening points. However, although the manufacturing process margin is reduced,
It can also be controlled only by the firing conditions. A fourth embodiment will be described below. The figure referred to is FIG. 9 as in the second embodiment. In the same way as in the second embodiment,
After forming a color filter layer (pigment fine particle layers 25, 26, 27) composed of red, green, and blue pigment fine particles, a paste mainly composed of a low melting point lead glass powder having a softening point of 470 ° C. is printed and dried. And baked at 500 ° C. to form a first insulating layer 28 having a thickness of about 8 μm. Next, the same low-melting-point lead glass paste was printed, dried, and fired again at 550 ° C. to form the second insulating layer 29. Like this
The insulating layer covering the pigment fine particle layer is divided into two layers, and the first glass layer covering the pigment fine particle layer is baked once at a low temperature so that the low-melting-point lead glass paste reprinted on the first glass layer can be further cured. Even at a high temperature, the effect on the pigment fine particle layer could be avoided. Of course, when the firing temperature is high, the pigment fine particle layer is diffused, aggregated, cracked, and deformed due to flow. If the firing temperature is low, problems such as a decrease in dielectric strength and the retention of bubbles may occur.
Although the process margin was smaller than that of the second embodiment, a color filter having good characteristics was obtained by separately firing the two insulating layers while changing the firing temperature. In this case, a plurality of insulating layers can be formed by the same paste printing, thereby reducing the process cost. Note that this method can also be applied to the structure of the third embodiment.

In order to realize a panel in which a fine pigment fine particle layer is covered with an insulating layer only by this firing temperature, the optimum firing temperature depends on the low melting point lead glass material used for the insulating layer. The difference between the first firing temperature directly covering the layer and the next higher firing temperature was preferably between 20 ° C and 80 ° C.

The average particle size of the pigment fine particles and the thickness of the pigment fine particle layer used in the first to fourth embodiments have a great influence on the characteristics of the color filter. The average particle size of the pigment fine particles is related to the cracking of the pigment fine particle layer during the insulating firing and the transmission spectrum, and the average particle size is from 0.01 to 0.1.
A color filter having a size of 15 microns and having no cracks and excellent in selective transmission characteristics could be obtained. As shown in FIG. 11, when the average particle size of the pigment fine particles increases, the scattered light increases from around 0.15 μm and the parallel light transmittance decreases. For this reason, when the average particle size increases, the transmittance of the color filter decreases and the display surface becomes cloudy due to scattering of external light, so that the contrast decreases. On the other hand, if the average particle size is reduced to 0.01 μm or less, cracks are likely to occur in the pigment fine particle layer, probably because the cohesive force increases. FIG. 12 shows an example. The crack gap of the pigment fine particle layer on the vertical axis is a gap width of a crack generated in the pigment fine particle layer. When the cracks are present, the amount of transmitted white light increases and the selective transmission characteristics of the color filter decrease. From the above, in the present embodiment, the average particle size of 0.0
Pigment fine particles of about 3 microns were mainly used.

FIG. 13 shows the dependence of the parallel light transmittance of the pigment fine particle layer on the film thickness. The characteristics of FIG. 13 show that the wavelengths of 610 nm and 515 which are the emission peaks of the red, blue, and green
9 is a plot of transmittance at 455 nm, 455 nm, and transmittance at 555 nm, 618 nm, and 585 nm of the absorption peak of the color filter. However, the red filter has a transmission spectrum similar to that of an edge filter.
5 nm was taken as the wavelength of the absorption peak.

The color filter characteristic that can obtain higher contrast is that the difference between the round plot, which is the emission wavelength of the phosphor, and the square plot, which is the absorption wavelength of the filter, is large in FIG. That is, the emission color,
It is necessary to have a property of selectively transmitting red, blue, and green and blocking light of other wavelengths. From FIG. 13, if the thickness of the pigment fine particle layer is too thick, the overall transmittance decreases, so that there is obtained a transmission characteristic in which there is no difference between the circle plot and the square plot. From this, it was found that the optimum range of the thickness of the pigment fine particle layer was 5 μm or less.

If the thickness of the pigment particle layer is too small, the wavelength dependence of the transmission spectrum is weakened, and the spectrum becomes gentle as a whole, and the selective transmission characteristics are lost. This is because if the ratio of the pigment fine particles in the pigment paste is extremely reduced, the optical density of the color filter layer is reduced, and the dispersion is significantly deteriorated due to the cohesive force between the pigment fine particles. from now on,
The optimum thickness of the pigment fine particle layer was found to be 0.5 μm or more.

From the above, it has been found that the optimum thickness of the optimum pigment fine particle layer for obtaining high contrast color filter characteristics is 0.5 to 5 μm. However, FIG.
As can be seen from FIG. 3, when the thickness of the pigment fine particle layer exceeds 3 microns, the transmittance of the phosphor at the emission wavelength clearly decreases. From the viewpoint of emphasizing light emission luminance, it can be said that the thickness of the pigment fine particle layer is more preferably in the range of 0.5 μm to 3 μm.

The relative dielectric constant of lead glass having a low melting point used as an insulating layer is considerably large, such as about 13, but the relative dielectric constant of pigment fine particles is often smaller than that of lead glass having a low melting point. In addition, the dielectric constant was further reduced probably because very small gaps remained between the particles in the pigment fine particle layer. Therefore, the insertion of the pigment fine particle layer tends to increase the discharge voltage. When the thickness is very small, the increase in the discharge voltage is negligible, but when the pigment fine particle layer has a thickness of 5 μm or more, the discharge voltage increases by 10 V or more,
It was disadvantageous in terms of panel drive. In the present embodiment,
The thicknesses of the red, blue, and green color filters were set to 1 to 2 microns within this optimum thickness range.

The optimum film thickness is not limited to an AC type plasma display panel in which a pigment fine particle layer is coated with a low melting point lead glass, but a plasma display panel having a structure in which the pigment fine particle layer is directly exposed in a discharge space. But the same is true.

In the above embodiment, an example is shown in which a color filter layer composed of a pigment fine particle layer for all three colors of red, green, and blue is formed. The pigment fine particle layer of the present invention may be formed for only two colors or one color.

In the above-described embodiment, only the panel having the AC surface discharge type structure has been described. However, it goes without saying that the present invention can be applied to an opposed two-electrode type AC plasma display or the like.

[0082]

According to the present invention, instead of dispersing the conventional colored pigment powder in the insulating layer of the glass layer, a thin layer mainly composed of pigment fine particles having a very fine particle diameter is used as a color filter, so that a high-temperature sintering process is performed. And the reaction deterioration is small. This is because the pigment fine particles are in a very dense layer state, and the amount of contact and reaction with the glass material as a whole is small. When baked in contact with the insulating layer of low-melting lead glass, the low-melting lead glass softens, causing interpenetration. However, since the pigment particles are very fine, they adhere relatively strongly to each other. The amount of pigment particles that diffuse into the low-melting lead glass layer is small, and the amount of glass material that penetrates into the pigment layer is very small because the gap between the pigment particles is very small. . For this reason, even if the same pigment fine particles were used, a color filter with less scattering caused by the difference in refractive index and good transmittance was obtained as compared with the case where the pigment particles were dispersed in the glass layer. In addition, by making the insulating layer in contact with the color filter layer a material having a high softening point, the above-described reaction and mutual penetration can be more effectively prevented, flow deformation due to reflow, aggregation of pigment particles, and pigment layer Cracks and the like were reduced, and a color filter with a uniform and fine pattern was realized.

By employing the panel incorporating the pigment fine particle layer of the present invention described above, it was possible to suppress the reflection of external light and realize a color plasma display panel having high contrast even in a bright place. Also,
Visible light emission of the discharge gas and unnecessary light emission of the phosphor can be effectively cut off, which is also effective in improving color purity.
The pigment fine particle layer can be easily formed by the process added to the formation of the insulating layer when manufacturing the front substrate of the AC type plasma display panel, and the cost associated with the formation of the color filter layer is not great and industrially. Can also be easily adopted.

[Brief description of the drawings]

FIG. 1 is a sectional view of a panel structure of a color plasma display panel according to a third embodiment of the present invention.

FIG. 2 is a sectional view of a panel structure of a color plasma display panel according to a third embodiment of the present invention.

FIG. 3 is a graph showing a change in a transmission spectrum of a blue color filter.

FIG. 4 is a graph showing a change in a transmission spectrum of a red color filter.

FIG. 5 is a sectional view of a conventional color plasma display panel.

FIG. 6 is a cross-sectional view of a conventional color plasma display panel.

FIG. 7 is a cross-sectional view of a conventional color plasma display panel.

FIG. 8 is a sectional view of the panel of the color plasma display panel according to the first embodiment of the present invention.

FIG. 9 is a sectional view of a panel of a color plasma display panel according to a second embodiment of the present invention.

FIG. 10 is a sectional view of a panel of a color plasma display panel according to second and third embodiments of the present invention.

FIG. 11 is a graph showing a relationship between a pigment average particle diameter and a parallel light transmittance.

FIG. 12 is a graph showing a relationship between an average pigment particle size and a crack gap of a pigment fine powder layer.

FIG. 13 is a graph showing the relationship between the pigment fine particle layer thickness and the parallel light transmittance.

FIG. 14 is a sectional view of a conventional color plasma display panel.

FIG. 15 is a sectional view of a conventional color plasma display panel.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 front substrate 2 transparent electrode 3 buffer layer 4 transparent insulating layer 5 black partition 6 white partition 7 white insulating layer 8 rear substrate 9 data electrode 10 phosphor (red) 11 phosphor (green) 12 phosphor (blue) 13 color filter (Red) 14 Color filter (Green) 15 Color filter (Blue) 16 Protective layer 17 Transparent insulating layer 18 Discharge cell (Red) 19 Discharge cell (Green) 20 Discharge cell (Blue) 25 Pigment fine particle layer (Red) 26 Pigment fine particle Layer (green) 27 Pigment fine particle layer (blue) 28 First insulating layer 29 Second insulating layer 30 Black matrix

Claims (16)

(57) [Claims] 1. A color plasma display panel having a transparent electrode coated on an insulating layer, wherein the insulating layer is formed by laminating a buffer layer directly covering the transparent electrode and an insulating layer having a color filter function. A color plasma display panel, wherein the insulating layer having a layer structure and having the function of the color filter is formed by patterning a pigment powder and coating and firing a transparent low melting point lead glass. 2. A color plasma display panel having a transparent electrode coated on an insulating layer, wherein the insulating layer is formed by laminating a buffer layer directly covering the transparent electrode and an insulating layer having a color filter function. The insulating layer having a layer structure, and having the function of the color filter, is formed by patterning a mixture of a pigment powder and a photosensitive material, and then coating and firing a transparent low melting point lead glass. A color plasma display panel characterized by the following. 3. The buffer layer is made of alumina.
The color plasma according to claim 1 or 2, wherein
Display panel. 4. The buffer layer is made of silicon oxide.
The color plasma according to claim 1 or 2, wherein
Display panel. 5. The color plasma display panel as claimed in any one of claims 1 to 4 wherein the transparent electrode is characterized by comprising tin oxide. Wherein said color plasma display panel according to claim 1, any one of 4 transparent electrodes, characterized in that the indium tin oxide. 7. A plasma display panel having at least a discharge electrode and an insulating layer formed on a front substrate serving as a display surface side, wherein the insulating layer is formed on the discharge electrode and formed independently of the insulating layer. A color plasma display panel, characterized in that a thin color filter layer containing the fine pigment particles as a main component is formed between the insulating layer and the discharge electrode formed on the substrate. 8. claims, characterized in that the insulating layer is formed between the thin color filter layer mainly composed of the discharge electrodes and the pigment particles formed independently of the insulating layer 7 The color plasma display panel according to the above. 9. A first insulating layer formed on a discharge electrode, a thin color filter layer mainly composed of pigment fine particles formed on the first insulating layer, and a thin color filter layer mainly composed of the pigment fine particles. The color plasma according to claim 8, further comprising a second insulating layer formed on the color filter layer, wherein a softening point of the first insulating layer is higher than a softening point of the second insulating layer. Display panel. 10. A method of manufacturing a color plasma display panel having a transparent electrode covered with an insulating layer, wherein a thin color filter layer mainly composed of pigment fine particles is formed and then a thin color filter layer mainly composed of said pigment fine particles is formed. A firing temperature of an insulating film having a softening point in contact with the insulating layer is higher than the softening point, and firing is performed at a temperature at which the pigment is not dispersed in the insulating layer. 11. A method of manufacturing a color plasma display panel having a transparent electrode coated on an insulating layer, wherein the first insulating layer is fired, and then a thin color filter layer containing pigment fine particles as a main component is formed. Forming a second insulating layer and firing the second insulating layer at a temperature higher than the softening point of the second insulating layer and at a temperature at which the pigment is not dispersed in the insulating layer. A method for manufacturing a plasma display panel. 12. A method for manufacturing a color plasma display panel having a transparent electrode covered with an insulating layer, wherein the first insulating layer is fired, and then a thin color filter layer containing pigment fine particles as a main component is formed. After the second insulating layer, a third insulating layer lower than the softening temperature of the second insulating layer is formed, and the first and second insulating layers are fired from the softening point of the first insulating layer. And baking at a temperature at which the pigment is not dispersed in the insulating layer and then baking at a temperature at which the third insulating film is flattened by the baking. 13. The color plasma display according to claim 1, wherein the thickness of the thin color filter layer containing pigment fine particles as a main component is 0.5 to 5 μm. panel. 14. A thin film containing the pigment fine particles as a main component.
The thickness of the color filter layer should be 0.5 to 3 microns.
13. The method according to claim 1, wherein:
Color plasma display panel. 15. The method according to claim 1, wherein the thin color filter layer containing the pigment fine particles as a main component is formed of pigment powder having an average particle diameter of 0.01 to 0.15 μm. 2. The color plasma display panel according to item 1. 16. A thin film containing the pigment fine particle layer as a main component.
A color having a color filter layer and an insulating layer covering the color filter layer
In the method for manufacturing a plasma display panel,
An insulating layer comprising at least two or more layers;
The insulating layer covering the filter layer directly from above is
First baking at a temperature that does not adversely affect the luster layer
Forming step and the firing temperature of at least one of the other insulating layers
With the second baking step which is higher than the first baking step
A color comprising at least two firing steps
-Manufacturing method of plasma display panel.